Signaling system



April 29, 1930.

c. L DAVIS SIGNALING SYSTEM Filed Aug. 21,

Y 1928 2 Sheets-Sheet l @erwten v f/ April 29, 1930. C, L. DAVIS 1,756,086

SIGNALING SYSTEM F'led Ag. 21, 1928 2 Sheets-Sheet 2 5gg-m INVENTR. when i@ @ow/vlo,

I BY

/ f/ ATTORNEY.

Patented Apr. 29, 1930 UNITED STATES PATENT OFFICE CHESTER L. DAVIS, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO WIBED RADIO, INC., OF NEW YORK, N. Y., A.CORPORATION 0F DELAWARE SIGNALING SYSTEM Application led August 21, 1928. Serial No. 800,979.

My invention relates to `.signaling systems in general and more speciicallyto systems for the transmission and reception of pictures by space radio o r wired radio systems.

An object of my invention 1s to prov1de an improved system for the transmission of pictures. v

Another object of my invention is to provide an improved system for the reception of pictures.

Still another object of my invention is to provide a system for the reception of pictures, views and the like without the neces-y sity of the usual methods of synchronizing the receiver vwith the transmitter.

A further object of my invention is to provide a system for the transmission of pictures, views and the like whereby a receiving system, employing a glow-discharge device similar to that described in my co-pending application Serial No. 299,501, led Aug 14, 1928, entitledGlow discharge device, may receive the transmitted pictures without distortion of the reproduction and without -troublesome synchronization as usually required. I l

A better understanding of the signaling system of my invention can be had by referring to the specification following and to the accompanying drawings, wherein, lFigures 1 and 2 are illustrations showing the transmitting part of the signaling system of my invention; Figs. 3 and 4 are illustrations showing the receiving part-of the .signaling system of my invention; Fig. 5 is a graph showing the operation of the transmitting part of the signaling system of my invention; Figs. 6 and 7 are schematic circuit arrangements employed in the receiving system and Fig. 8 is aV graphical representation showing the operation ofthe signaling system of my invention. -o

In systems heretofore employed in the transmission and reception of pictures, views and moving pictures, an elaborate method of synchronization has been employed to synchronize the receiver with the transmitter.

A Vscanning disk has heretofore been employed at both receiver and transmitter.

The purpose of the scanning disk is to interning system employed at the transmitter.

The disadvantages of-such a `system are well known to those skilled in the art. In the signaling system of my invention, such synchronization is eliminated and the simplicity 'of operating procedure is lgreatly reduced thereby. A better understanding can be had by referring to the accompanying drawings.

Fig. l shows the transmitter employed in the signaling system of my invention. The object represented at I-I is illuminated by suitable means 30 and rays of light from the 'object H enter the lens 6 which are interrupted by scanning disk 7. v Scanning disk 7 may be of any suitable construction or may be a shutter or perforated band. A common the intensity of the light rays, are caused tof 4 modulate the transmitter and the signal thus transmitted at a frequency corresponding to the frequency characteristics of the oscillatory circuit thereof. In the signaling system of'my invention, the frequency of the transmitted energy is varied corresponding to the position of the scanning member 7. A continuously variable frequency controlling member, herein represented as capacity 9, is

method of scanning employs a disk having perforations aroundl the.

associated with the scanning member 7 whereby variations in the frequency are caused at each rotation of the scanning meinber 7. Thus variations of frequency are transmitted, each frequency having a value of current corresponding'to the resistance of photo-electric device 5 at each instant. Ciapacity 9 is herein illustrated connected in series with photo-electric device and the 1nput of transmitter 1. Capacity 9 may be shunted by an impedance unit. Input terminals 3 may -connect to the modulation circuit of a transmission system. Connected to the control electrode and cathode elect-rode of a thermionic tube, the amplified energy vin the anode circuitwould have a frequency value depending upon the value ofthe exciting frequency from capacity 9 and any value of impedance employed therewith. The transmitted `,signaling energy will be modulated at a continuously variable audio frequency. The current or percentage modulation depends upon the resistance of photoelectro device 5. It is obvious thatan impedance may be caused to vary with the rotation of the scanning member accomplishing a similar periodically varyingaudio frequency modulation. The high frequency signaling energy may be associated with a load circuit 2.

Fig.' 2 shows another form of the signaling system of my invention wherein the reference characters correspond to those i of Fig. 1. Photo-electric device 5 is associated with the `input'terminals 3 of an amplifier-modulatoil unit 10. Amplifier-modulator unit 10 may comprise thermionic tubes, the terminals 3 connecting to the control'electrode and cathode electrode of a thermionic tube amplifier. Variations in the intensity of light entering lens 6 and caused to be incident upon lightsensitive or photo-electric device 5 produce variations of current which are amplified and caused to modulate the generated energy of oscillator 11. The ouput of oscillator 11 may be associated with any suitable load circuit 23, 2b. The high frequency circuit of oscillator 11 or load circuit 2, 2b may be controlled by periodically changing frequency unit 9, herein represented as a capacity unit connected in series vwith the'ground circuit 2. It is possible that the energy in the load circuit ma be of great value. In such a case the perio ically changing frequency unit 9 may be associated with the master oscillator unit, if such is employed, or the input ciiicuit of the oscillator. In this arrangement the high frequency signaling energy is notV of a constant frequency value but covers a band of different frequencies in repeating successions. Any variable frequency unit may-be associated with scanning member 7 for causing a variation in the frequency of the transmitted signaling energy.

Figs. 3 and 4 are illustrations showing the receiving unit of the signaling system of my invention. Collecting system 2**--2h receives a signal as transmitted from a transmitter similar to that shown in Fig. 1. In Fig. 3 the high frequency signaling energy is amplified, rectified and the audio frequency signal is amplified by unit 14. Unit 14 may comprise a thermionic tube circuit arr'an ement. The output terminals 15 of the au 'o frequency amplifier may be associated with glow-discharge device 12--13. Glow-discharge device 12-13 may be of the design as described in my co-pending application Serial No. 299,501 filed Aug. 14, 1928. Standing waves are set up in winding 13. Winding 13 is enclosed by an evacuated envelopev 12 containing an inert gas such as neon, krypton or any gas which will give a luminous radiation. Potential nodes and anti-nodes are set up in winding 13, the position along winding 13 depending on the frequency of the modulated energy. The potential loops or where the potential is maximum is where the luminous radiation will take place. This position shifts with the frequency. The extent of luminous radiation or intensity of light at such position corresponds to the light and dark portions of the transmitted picture or scene.

Fig. 4 shows another modification of the receiving. unit employed in the signaling system of my invention. This unit is designed to operate and reproduce pictures and views similar to the unit shown in Fig. 3, however it is adapted to receive a periodically varying frequency and modulated signal as transmitted by a transmitter designed similar to that shown in Fig. 2. The high frequency signaling energy is received by collector system 2**-2 Collector system 2& 2b may have aperiodic frequency characteristics. The high frequency signaling energy may be amplified by amplifier 16. Amplifier 16 may have sufficient aperiodic frequency characteristics whereby the band of frequencies transmitted may be amplified. A glow-discharge device 12-13 is connected to any suitablel output circuit of amplifier 16 where standing vwaves are set up. radiation and shifting of the illuminated area is similar to the operation of glow-dischargedevice 12-13 of Fig. 3.

Fig. 5 is a graphical representation of the relation between the rotation of the scanning disk at the transmitter and the frequency of the transmitter circuit. In the arrangemnet shown in Fig. 1 the frequency variation is in the band of audio frequencies. The graphicalv representation muld therefore show the relation between the audio frequency band of modulation or particular freuency of modulatiom represented b the c aracterF 1n the graph, andthe position of the scanning disk represented in degrees of rotation.

The luminous Fig. B is a schematic illustration showing the immediate connections to the glow-discharge device 13. Circuits 18'L and 18", having inherent frequency characteristics may be associated with the source of signaling energy by switch members 18 and 19 respectively. Circuits 18* and 18b may be common to the winding 13 of the glow-discharge device. Terminals A and may be connected to the source of signaling energy. Standing waves are set up in the winding 13. By adjusting the frequency characteristics of circuits 18" and 18h the potential loops may be adjusted along the conductor. Thus the potential distribution in winding 13 may be controlled. Without this adjustment the the frequency' receiver would operate on only band corresponding to the fr'elllency characteristics of the respective win 'ng 13.

Fig. 7 is a schematic diagram showing the adjusting circuit 18-18 for shifting the potential loop along the length of windin 13 in the glow-discharge device. A metal p ate 20 may be placed adjacent to winding 13.

Winding 13 may have one end open, the other end and metal plate 20 connected to the source of signaling energy A+B. The arrangement of metal plate 20, constituting one electrode ofthe glow-discharge vdevice is described in In co-pending application, Serial No. 299,501 led Aug. 14, 1928.

Fig. 8 is a graphicalrrepresentation showing one relation between the wave length characteristics of the glow-discharge device and the wave length 'of the received signaling energy. The wave length of the signaling energy is represented by the vertical line A. The wave length characteristics of the glow-discharge device may be represented by the horizontal line A. length of the signaling energy A' to the wave length characteristics of the glow-dischargeI device A may be approximately, two to one. The graph may also be taken to represent the response area as shown by the line response.

At the transmitting station the scanning member selects different areas of the picture to be transmitted. Simultaneously and interdependent with such selection of the different areas, a frequency variation of the transmitted energy is effected. Different frequencies are transmitted for different areas of the picture. Such frequencies may be audio frequency modulations of the carrier frequency or may be variations ofthe carrier frequency itself. The scanning device may be any suitable arrangement such as the spiral disk commonly employed where the lines are drawn across the .horizontal length of the picture or where they are drawn across the vertical length of the picture. Other scanning means such as vibrating tuning forks moving in different planes may be employed. Such scanning means are well known to those skilled in the art. The scanlof the glow discharge device at must be modified 1n accordance with the The ratio of the wave ning may be in'diagonal order if so desired,

however the design of the glow discharge vscanning and the design of the glow dis- The design j charge device at the receiver.

the receiver type of scanning employed and of course with the proper frequencycharacteristics to respond to the variable frequency energy. The position of the nodes or of the 'antinodes o energy in the glow discharge device may be emp oyed to reproduce either a positive or negative of the original picture. Suppose as an example of design we choose to` make the inductance of each length of wire in the horizontal plane of the value n and that 41 ofsuch-lengths are employed giving us a total inductance of approximately 41a. The total frequency variation at the transmitterwhich corresponds to the different areas of the picture will be such as to shift the potential distribution in the glow discharge device the full length of the complete inductance 14n. It follows that as each of the apertures in the scannin disk scan one line horizontally across the picture, the frequency of the transmitted energy is varied sufficiently to cause a change in the distribution in the glow discharge device at the receiver over one length of wire in the horizontal plane. The succeeding aperture may not scan the next line of the picture at the transmitter but scan the third line. The usual frequency variation during the interval between the scanning by the two aper tures may be effected. The next exposure at the receiver will be the third horizontal line because of the frequency shift at the transmitter. Atthe bottom of the picture the scanning may now continue from the bottomV to the top interleaving with the lines previously drawn across the picture in the horizontal plane or may continue from the second horizontal line from the top, followed by the even numbered lines. The frequency -varying device may be caused to respond through a second cycle where the first frequency transmitted would be such as to cause a change in the potential distribution along the second horizontal line where the inductance thus far would be of the order of 2n. Many different arrangements may be employed all with equally satisfactory results, some arrangements provide greater persistency of vision than do others and are less costly to manufacture, however, accuracy in the initial selection of the glow discharge device is the main requisite to satisfactory results.

In Figs. 5 and 8 the numerical values shown are arbitrary and it is not intendedto restrict the embodiments of my invention ais going specification thereb In Figs. 1 to 4 inclusive, the peri picture. At the receiver the incoming en.

ergy is distributed along a conductor which distributionchanges with the frequency of the incoming energy and occupies positions along the conductor corresponding to theA re- `spectine portions of the picture transmitted.

Theadvantages of the signaling s stem of my invention are many. Among t em, the following are most obvious:

1. Transmission and reception of moving or stationary scenes or pictures without distortion. t

2. Simplicity o f operation at both the transmitting and receiving ends.

,3. synchronizing dispensed with at the receiving end.v

I realize that many modifications of the signaling system of my invention arepossible without departing from the spirit of my in vention and it is to be understood that my invention shall not be restricted by the foreor by the accompanying drawings but onl the appended clalms. l y

What I claim as new and desire to secure by Letters Patent of the,United States is as follows:

1. A television receiver comprising in combination means for receiving variable frequency energy, variable intensity apparatus comprising a coil having its inductance distributed in a plurality of sections disposed in horizontal planes parallel to each other and a glow discharge tube enveloping the different sectionsof said inductance.

2. In a television receiving system the combination of a luminously responsive device comprising an inductance coil having its inductance distnibuted along a plurality of parallel sections in different horizontal planes and a luminously responsive gas en- I velope surrounding said inductance coil for indicating the potential distribution along said coil.

3. -Inn a television receiving system the combination of a circuit for .receiving signaling ener of variable frequency corresponding to di erent shaded areas of a transmitted picture, an inductance comprising a plurality of parallel longitudinally extending sections as defined in the scope ofnal receiving circuit, a receiving screen com.-

prising a multiplicity of inductance members connected with said circuit and extending in a plurality of parallel planes, said members being associated with a body of luminously responsive gas whereby changing potential distribution in said inductance members causes changes in luminosity from .diiferent areas of said body of gas.

6: A method of indicating positions by varlable frequency energy which consists in establishing potential nodes along different sections of luminously responsive inductance units arranged in parallelpaths'.

. 7. An apparatus of the class described comprising a wave receiving inductance element divided into a plurality of -parallel longitudinally extending sections and means for automatically and luminously indicating changes in position of a potential node established alon said element.

8. The. met od of indicating positions which consists in changing the location of otentialy nodesin accordance with a varia le signal and causing said changing of nodes to be luminously visible along a plurality of parallel sections of inductance extending in a longitudinal plane.

9. In the art of transmitting vision, a rei ceiving apparatus for waves of varying lengths comprisin a luminously responsive lnductance divide into a plurality of parallel and longitudinally extending sections.

1Q. In the art of transmittingy vision, a receiving apparatus for waves of varying lengths comprising a luminously responsive inductance divided into a plurality of p arallel and longitudinally extending section, said sections var ing in luminosity in accordance with the di erent areas of a transmitted picture.

11. In the art of transmitting vision, receiving apparatus for waves of varying lengths comprising means for setting .up standing waves in a luminously responsive inductance, said inductance comprising a plurality of parallel arranged conductors connected in series and glow discharge apparatus adjacent said conductors for indicating the potential distribution therein.

12. In a television system, a conductor bent upon itself in a plurality of parallel paths and means for causing a luminous spot to move along said conductor according to the potential distribution therein in said plurality of `'ploying a line scanning s stem for picture transmission, a luminous y responsive receiving screen comprising a plurality of conductors electrically connected in series and positioned in parallel planes of a number and and in the manner substantially the same as the lines drawn across the transmitted picture.

15. In the art of transmitting vision, a luminously responsive screen comprising a plurality of electrical conductors arranged 1n a plurality of substantially parallel planesv corresponding to the transmitted lines of a picture.

16. In the art of transmitting vision employing a line vscanning system for picture transmission, aluminousl res onsive receiving screen comprising a p urality of electrical conductors associated with a body of inert gas, said conductors being arranged in a pluralit of parallel planes corresponding in num er and arrangement to the different .lines described across the transmitted picture.

17 A television system comprising means for transmitting variable frequency signals, means for receiving variable frequency signals, and a screen for visually reproducing the variable frequency signals comprising a multiplicity of parallel extending luminous portions electrically connected to each other and with said receiving means.

18. A television system comprising means for transmitting variable frequency signals, means for receiving variable frequency signals, a screen for visually reproducing the variable frequenc signals comprising a multiplicity of para lel extending luminous portions electrically connected to each other and with said receiving means, and means connected with said screen for shifting the osition of potential nodes therein to pre etermind positions along said parallel extending luminous portions.

19. Iii a television system, means for transmitting signaling energy over a variable y range of frequencies, means vfor receiving the transmitted energy, a screen comprising a plurality of parallel extending portions connected with said receiving means and a tuning element connected to said parallel extending portions for predetermining the position of pontential nodes along said parallel extending portions.

Q0. In a television system, means for transmitting variable signaling energy, means for receiving the transmitted energy and a screen comprising a plurality of parallel extending portions connected in series, and a variable iiiductancc connected between said parallel extending portions and saidreceiving means for predetermining the position of potential nodes along said parallel extending portions.

In testimony whereof I affix my signature.

CHESTER L. DAVIS. 

